A check valve can be located in an intake passage leading to a cylinder of an engine to obstruct flow of fluid out of the cylinder back into the intake passage. Such fluid back-flow into the intake passage can cause the pressure therein to increase since such fluid back-flow is obstructed by the check valve. During ordinary operation, it may be desirable to maintain this increased pressure in the intake passage since it can resist further fluid back-flow out of the cylinder.
One factor considered in the construction of a check valve is the maximum pressure of the fluid back-flow since it is desirable that the check valve be capable of withstanding such a pressure. This maximum pressure can occasionally be quite high, such as during a backfire.
Constructing a check valve capable of withstanding high pressures can detract from other aspects of the check valve. For example, such a check valve can comprise a reed valve. Increasing the thickness of the petal of a reed valve can increase the ability of the reed valve to withstand high pressures. But, increasing the thickness of the petal can result in a higher mass and stiffness of the petal, which can increase the stress in the petal and the resistance of the petal to fluid flow toward the cylinder.